Electronic climate control systems for motor vehicles typically include one or more zones controllable by adjusting the temperature of air flowing into each zone (and even the rate of air flow) in accordance with temperature or comfort set points which are set by occupants of each zone and sensed air temperature in each zone. Other factors such as outside temperature and sun load which are important to occupant comfort are measured and included in a control algorithm which determines adjustments to temperature and air flow.
The sun load can have a significant effect on comfort since it impacts the overall comfort and especially has an impact when it shines directly on one or more occupants. Generally sun load is measured by solar sensors placed to detect sun light from any direction to determine a measure of the overall heat load from that source. Such measurement does not however distinguish between the effect on individuals who are exposed directly to the sun load and those who are shaded by the roof of the vehicle. As a result, the various zones receive the same adjustment for sun load while the occupants receive different amounts of sun load.